Thumb Hypoplasia

What Is Thumb Hypoplasia?

Babies with thumb hypoplasia are born with a thumb that is smaller than normal,
or with the thumb missing completely. Sometimes the bones of the wrist or arm are
smaller or missing too. Thumb hypoplasia can happen on one or both hands.

What Causes Thumb Hypoplasia?

Thumb hypoplasia (also called hypoplastic thumb) happens before
a baby is born. When a baby's hands are first forming, they are shaped like mittens.
Then the fingers and thumb develop. In babies with thumb hypoplasia, the thumb does
not form completely. Thumb hypoplasia is not caused by anything a mother did or did
not do while pregnant.

Who Gets Thumb Hypoplasia?

Any baby can be born with thumb
hypoplasia
. Sometimes, it happens as part of a genetic
syndrome
.

How Is Thumb Hypoplasia Diagnosed?

A prenatal ultrasound might
show thumb hypoplasia. Otherwise, doctors diagnose it when a baby is born.

X-rays of the bones in the thumbs and
hands will help the surgeon decide on the best kind of treatment. Other tests might
be done to see if the thumb hypoplasia is part of a genetic syndrome.

How Is Thumb Hypoplasia Treated?

The thumb is a very important part of the hand. Surgery is usually recommended
to improve a small or weak thumb. If the thumb is missing, the index finger can be
made into a new thumb (this is called
pollicization
).